Integrated MEMS packaging

ABSTRACT

An integrated MEMS package and associated packaging method are provided. The method includes: forming an electrical circuit, electrically connected to the first substrate; integrating a MEMS device on a first substrate region, electrically connected to the first substrate; providing a second substrate overlying the first substrate; and, forming a wall along the first region boundaries, between the first and second substrate. In one aspect, the electrical circuit is formed using thin-film processes; and, wherein integrating the MEMS device on the first substrate region includes forming the MEMS using thin-film processes, simultaneous with the formation of the electrical device. Alternately, the MEMS device is formed in a separate process, attached to the first substrate, and electrical interconnections are formed to the first substrate using thin-film processes.

RELATED APPLICATIONS

This application is a continuation-in-part of a pending patentapplication entitled, PIEZO-TFT CANTILEVER MEMS, invented by Zhan etal., Ser. No. 11/031,320, filed Jan. 5, 2005. This application isincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention generally relates to the packaging ofmicroelectromechanical systems (MEMS) and, more particularly, to asystem and method for simultaneously packaging a MEMS device with activecircuitry on an integrated circuit (IC) substrate.

2. Description of the Related Art

MEMS devices are typically made on silicon wafers; using one of two wellestablished techniques: bulk micro-machining or surface micro-machining.In both of these methods, the MEMS device is fabricated on a siliconwafer using standard IC-type fabrication equipment. Once the wafer isprocessed, the wafer is diced to form individual die. These MEMS die mayor may not be integrated with electronic components (on CMOS). Once thedie is cingulated, it must then be packaged in some form of package,similar to an IC package. This package is eventually inserted into asocket or bonded to a Printed Circuit Board (PCB) as part of an overallsystem, i.e., a cell phone. These packages can be quite elaborate,depending on the MEMS style and application, including vacuum packagerequirements. In addition, because many MEMS devices are required tomove during operation, the package must provide a cavity that allows forthis movement.

One problem with this type of MEMS packaging methodology is that thepackage is a very large proportion of the total MEMS device cost; on theorder of 30–70% of the overall cost. This packaging cost can, therefore,have a significant impact on the capability of such MEMS devices topenetrate cost-sensitive markets, such as the cell phone market.

Another problem with existing MEMS packaging is the noise inherent withthe electrical connections between the MEMS package and the rest of thesystem. The bonding, wiring, and electrical interconnections associatedwith interfacing a MEMS device embedded in a package, to a circuit,necessarily adds impedance mismatches that result in noisy or lowamplitude signals.

However, there is mounting evidence that MEMS technology can add valueto systems, such as cell phones, in a market that is ripe for newtechnology, if only the packaging issue could be addressed. Continuingwith the cell phone example, it is certain that the camera-on-cell phonehas made a great impact on the market. The search is on for the nextadded functionality that can drive new expansion of the cell phonemarket.

MEMS are being considered for the following cell phone functions:

1) Motion capture (Accelerometer and gyroscope);

2) Microphones;

3) RF devices and RF modules;

4) Image capture;

5) Low power solutions;

6) Identification (biometrics);

7) Enhanced display functionality; and,

8) Personal health and safety monitoring.

The issues preventing MEMS penetration into the cell phone market arecost and performance. As mentioned above, packaging is 30–70% of theMEMS device cost. This cost issue is preventing the integration of MEMSinto cell phones, display systems, and many other types of electronicdevices.

MEMS devices are a logical derivative of semiconductor IC processes thatmay be used to develop micrometer scale structural devices such astransducers or actuators, and they are typically fabricated on siliconsubstrates. MEMS devices typically interface physical variables andelectronic signal circuits. The integration of MEMS into larger scalesystems has been expensive to fabricate due to the process difficultiesand the cost associated with integrating the MEMS standard ICtechnologies, such as CMOS. The processes used to fabricate MEMS onglass offer the advantage that the integration of electrical andmechanical functions is easily done. In this way, system levelintegration is possible and cost effective.

It would be advantageous if MEMS devices could be packaged as part ofthe overall process of fabricating active devices on a circuit board ordisplay.

SUMMARY OF THE INVENTION

The problem solved by this invention is the creation of a low-costpackaging system for the integration of electrical, mechanical andoptical MEMS devices with electrical systems. By way of example, thepackaging of MEMS device on a display screen is presented (i.e., a cellphone display), but the invention is not limited to any particularelectrical system. Generally, it is assumed that the MEMS device to bepackaged can be any type of mechanical, electrical, optical, ormicro-fluidic device that requires encapsulation or packaging.

One aspect of this invention deals with the integration of MEMS on glasssubstrates using low temperature polysilicon technology. Using thisinvention, the MEMS device and amplification circuitry can be integratedtogether, monolithically fabricated on the glass substrate andencapsulated. The advantage of monolithic fabrication is the seamlessblending of electrical and mechanical devices in the polysiliconintegrated approach resulting in overall system electrical qualitybetter than, or similar to the approach where discreet MEMS packages areintegrated with standard integrated circuits.

Accordingly, a method is provided for packaging a MEMS device. Themethod comprises: forming an electrical circuit electrically connectedto a first substrate; integrating a MEMS device on a first substrateregion, electrically connected to the first substrate; providing asecond substrate overlying the first substrate; and, forming a wallalong the first region boundaries, between the first and secondsubstrates.

In one aspect, the electrical circuit is formed using thin-filmprocesses; and, integrating the MEMS device on the first substrateregion includes forming the MEMS using thin-film processes, simultaneouswith the formation of the electrical device. Alternately, the MEMSdevice is formed in a separate process, attached to the first substrate,and electrical interconnections are formed to the first substrate usingthin-film processes.

The wall formed along the first region boundaries may act to enclose theMEMS device between the first and second substrates. For example, theMEMS device may be hermetically sealed. Alternately, the secondsubstrate may have an opening through it, and the MEMS device may be anenvironmental sensor. The wall between the first and second substratethen acts to isolate the MEMS device from the electrical circuit, whileexposing the MEMS device to an environment via the second substrateopening. For example, the MEMS environmental sensor may be amicro-fluidic MEMS that is exposed to a fluid environment.

The wall between the first and second substrate may be a sealant bondingthe first substrate to the second substrate. Spacers may be used tomaintain a uniform distance between the first and second substrates. Inanother aspect, the wall is an O-ring held in place by grooves in thefirst and second substrates.

Additional details of the above-described method and an integrated MEMSdevice package are provided below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B is a partial cross-sectional and plan views,respectively, of an integrated microelectromechanical system (MEMS)device package.

FIG. 2 is a plan view showing an alternate configuration of the wallseparating the MEMS from the electrical circuit.

FIG. 3 is a perspective drawing showing a wall formed as part of aprefabricated separating assembly.

FIG. 4 is a cross-sectional view depicting a first alternate aspect ofthe integrated package of FIG. 1B.

FIG. 5 is a cross-sectional view depicting a second alternate aspect ofthe integrated package of FIG. 1B.

FIG. 6 is a partial cross-sectional view of a variation in theintegrated package of FIG. 1B.

FIGS. 7A and 7B are partial cross-sectional and plan views,respectively, of a liquid crystal display (LCD) integrated package.

FIGS. 8A and 8B are partial cross-sectional and plan views,respectively, of an alternate aspect of the integrated package of FIGS.1A and 1B.

FIG. 9 is a partial cross-sectional view showing an alternative walldesign.

FIGS. 10A and 10B are plan and partial cross-sectional views,respectively, depicting the encapsulation of a MEMS device on a displaysubstrate.

FIG. 11 is a flowchart illustrating a method for packaging a MEMSdevice.

DETAILED DESCRIPTION

FIGS. 1A and 1B is a partial cross-sectional and plan views,respectively, of an integrated microelectromechanical system (MEMS)device package. The MEMS integrated package 100 comprises a firstsubstrate 102 having a first region 104 with boundaries 106. Anelectrical circuit 108 is formed on a second region 110 of the firstsubstrate 102. The electrical circuit 108 is electrically connected tothe first substrate 102. For example, traces in the first substrate mayconduct dc power, ground, and electrical signals to the electricalcircuit 108. A MEMS device 112 is shown on the first region 104,electrically connected to the first substrate 102. The boundaries 105may, or may not completely form a perimeter that surrounds the MEMSdevice 112. A second substrate 114 overlies the first substrate 102. Awall 116 is formed along the first region boundaries 106, between thefirst substrate 102 and second substrate 114.

In its simplest form, the first substrate 102 is a one-sided board withelectrical traces on one of the surfaces. In this case, the electricalcircuit 108 and the MEMS 112 may be dice that are attached using ballgrid array (BGA) connections, or electrically connected using thin-filmprocesses such as metal deposition and selective etching. Typicallyhowever, the first substrate is made from multiple electrical layersseparated by interlevel dielectrics, as is common in CMOS and thin-filmprocesses. Low-temperature thin-film processes are often used if thefirst substrate is glass, plastic, or quartz, as would be the case if aliquid crystal display (LCD) is being fabricated. As shown, the MEMS 112is connected through via 118 and interlevel trace 120 to the electricalcircuit 108.

In some aspects, the electrical interconnection between the MEMS 112 andthe electrical circuit 108 may carry an electrical signal. For example,the MEMS 112 may trigger the gate of a TFT electrical circuit. In otheraspects, the MEMS 112 and the electrical circuit 108 merely share commondc voltages and grounds (the MEMS does not electrically communicate withthe electrical circuit). In another aspect, the MEMS 112 may beelectrically connected to other circuit boards via a connector to thefirst substrate 102 (not shown). For example, the MEMS device 112 may amicrophone mounted on the LCD screen of a cell phone, in communicationwith the cell phone transmission circuitry.

FIG. 2 is a plan view showing an alternate configuration of the wallseparating the MEMS from the electrical circuit. The wall 116 maycompletely enclose the MEMS 112, with the first substrate 102, thesecond substrate 114, along the first region boundaries 106, as shown inFIG. 1B. That is, the combination of substrates and wall form a cavityin which the MEMS 112 is seated. In one aspect, the wall hermeticallyseals the MEMS device 112 between the first substrate 102 and secondsubstrate 114 along the first region boundaries 106. Alternately asshown in FIG. 2, the MEMS 112 is separated from the electrical circuitbecause the electrical circuit 108 is completely enclosed by wall 116.Such an integrated package acts to generally protect the MEMS 112 whileexposing it to the ambient environment. The wall 116 may hermeticallyseal the electrical circuit 108.

FIG. 4 is a cross-sectional view depicting a first alternate aspect ofthe integrated package of FIG. 1B. The second substrate 114 has a thirdregion 400 with an opening 402, overlying the first substrate firstregion 104. The opening 402 exposes the MEMS device 112 to anenvironment. For example, the MEMS 112 may be an environmental sensor.The wall 116 isolates the MEMS device 112 from the electrical circuit108 along the first region boundaries 106. It may be undesirable thatthe electrical circuit is exposed to the environment seen by the MEMS.For example, the MEMS 112 may be microphone exposed to the ambientenvironment via opening 402.

FIG. 5 is a cross-sectional view depicting a second alternate aspect ofthe integrated package of FIG. 1B. Here, the MEMS 112 is a micro-fluidicMEMS, depicted as a piezo-TFT cantilever. The second substrate opening402 exposes the micro-fluidic MEMS to a fluid environment. Theintegrated package 100 may be immersed in a fluid, or as shown, thefluid is introduced to the opening 402 through a tube 500.

As shown, the electrical circuit 108 on the second region 110 of thefirst substrate 102 is an active circuit including a TFT, electricallyconnected to the MEMS 112 via a trace 504. The wall 116 along the firstregion boundaries 106 separates the TFT 108, exposed to a firstenvironment, from the MEMS 112, exposed to a second environment. Forexample, the first environment can be ambient atmosphere and the secondenvironment can be a fluid. As shown, in some aspects the wall 116 is acured sealant.

FIG. 6 is a partial cross-sectional view of a variation in theintegrated package of FIG. 1B. In some aspects, the wall 116 includesuniformly-sized spacers 600 embedded in a cured sealant 602, to maintaina uniform distance 604 between the first substrate 102 and the secondsubstrate 114. Alternately, as shown in FIG. 10B, a plurality ofuniform-shaped spacers applied to the first (or second) substrate 102.The wall is a cured sealant 602, with a uniform height 604 between thefirst and second substrates, response to the spacers 600.

FIGS. 7A and 7B are partial cross-sectional and plan views,respectively, of a liquid crystal display (LCD) integrated package. FIG.7A is not exactly drawn to the scale of FIG. 7B. The first substrate 102is an LCD display substrate (i.e., glass) with a perimeter 700. As inFIG. 1B, the MEMS 112 is enclosed by wall 116. The second substrate 114is a color filter substrate with a perimeter 702. Perimeter 700 cannotbe seen in FIG. 7B, but is approximately underlies perimeter 702(substrate 102 cannot be seen in the plan view). A seal 704 is formedalong the perimeters 700/702 of the display substrate 102 and colorfilter substrate 114. A cavity 706 is formed between the displaysubstrate 102 and the color filter substrate 114, bounded by the seal704. In one aspect, the cavity 706 is filled with liquid crystalmaterial. In this case, the wall prevents the liquid crystal materialfrom coming in contact with the MEMS 112.

In one aspect as shown, the color filter substrate 114 has a thirdregion 708 with an opening 710 through the substrate, overlying thefirst substrate first region 104. For example, the MEMS device 112 canbe a MEMS microphone. However, other types of MEMS devices can bepackage integrated into an LCD.

FIGS. 8A and 8B are partial cross-sectional and plan views,respectively, of an alternate aspect of the integrated package of FIGS.1A and 1B. The first substrate 102 includes a plurality of regions withboundaries. Shown are regions 800, 802, and 804, with respectiveboundaries 806, 808, and 810. The MEMS integrated package 100 furthercomprises a plurality of MEMS devices 812, 814, and 816 on the firstsubstrate 102, each in a corresponding region. A plurality of walls 818,820, and 822 are formed around the boundaries of a corresponding regionof the first substrate. FIG. 9 is a partial cross-sectional view showingan alternative wall design. The first substrate 102 includes a groove900 formed along the first region boundaries 106. Likewise, the secondsubstrate 114 includes a groove 902 formed in a region opposite thegroove 900 in the first substrate 102. In this case the wall 116 is anO-ring seated in the first and second substrate grooves 900/902. Thisarrangement permits a seal to be formed by merely clamping thesubstrates 102/114 together. Although only sealant and O-ring walls havebeen specifically depicted, the integrated package is not limited to anyparticular wall design. In some aspects not shown, the wall is formed bythe deposition and selective etching of field oxide. Alternately, thewall can be formed in conventional LC display substrate fabricationprocesses.

FIG. 3 is a perspective drawing showing a wall formed as part of aprefabricated separating assembly. A boundary assembly 300 is shownhaving the shape matching the first regions boundaries 106, and having aheight 302. Note, the assembly can be made from separate pieces thatmay, or may not interlock. The assembly pieces can be a conventionalrigid, semi-rigid, or even flexible plastic material. In this aspect,the wall 116 comprises the boundary assembly 300 attached to the firstsubstrate 102 along the first region boundaries 106, separating thefirst substrate 102 from the second substrate (not shown for clarity) bythe boundary assembly height 302. The boundary assembly can be fixed inplace by an adhesive or held in place by substrate friction.

Although only microphone and fluidic MEMS devices have been specificallydepicted, the present invention integrated package is not particularlylimited to any type of MEMS or MEMS function. For example, other MEMSthat can be packaged include an acoustic speaker, a radio frequency (RF)filter, an RF antenna, an accelerometer, a gyroscope, a chemical sensor,a temperature sensor, a humidity sensor, a pressure sensor, a lightsensor, an infrared sensor, or an actuator.

Functional Description

Conventionally, MEMS on display are packaged as discreet components inIC-like packages and then attached to the system using standard ICpackaging assembly techniques. This invention teaches a new way toestablish the MEMS package on the display itself, by utilizing theexisting display assembly process to create the package, resulting in ano-cost package for the MEMS device. Given the high cost of typical MEMSpackages, this invention has a clear advantage for display integrationand system level cost reduction.

FIGS. 10A and 10B are plan and partial cross-sectional views,respectively, depicting the encapsulation of a MEMS device on a displaysubstrate. Note, the MEMS device area (D3) is not to scale in FIG. 10B.The actual device area is much smaller, so as to not interfere with thedisplay operation. The invention creates a MEMS (or other device)encapsulation/package on a display substrate by using the standard cellprocessing in the LCD manufacturing process. The MEMS can be eithermonolithically fabricated on the display substrate during the arrayprocess, or transferred after the array process is complete. The MEMSdevices are encapsulated during the display cell process, with displaysubstrates on the top and bottom and sealant (bounding the glasssubstrates together on the sides). Referencing FIGS. 10A and 10B, anexemplary fabrication process follows.

1) A MEMS device (or other mechanical, electrical or optical device) isattached to a display substrate (S1), either through monolithicfabrication of the MEMS device during array fabrication or transfer ofthe device to S1 after array fabrication.

2) A counter substrate (S2) (color filter substrate in the case of manyLCD display processes) is prepared for mating to the first substrate(S1), to form a display device. Prior to bonding S1 and S2, spacers areapplied to one of the substrates to maintain even separation between S1and S2 after bonding. This is a standard LCD cell process.

3) A sealant is applied to either S1 or S2, forming the outline of atleast one display area and at least one separate area for devices (D3),such as MEMS.

4) S1 and S2 are bonded together forming a display device and anencapsulated package for the devices area (D3), bounded on the sides bythe sealant and the top and bottom by S1 and S2.

5) The display area likely undergoes further processing, such asinjection of liquid crystal material (in the case of LCD display).However, D3 can be protected from these additional processes by theencapsulation.

6) D3 can possibly be a vacuum package, depending on the processingsteps and environment of the processes that bond S1 and S2.

7) If it is desirable to expose device area D3 to the environment, thenone or both S1 and S2 may be pre-drilled in the area of D3 to providethis condition. This is desirable in the case where D3 houses anenvironmental sensor, for example.

8) Because the device area (D3) and the display area are separatelyencapsulated, there is no cross contamination.

Another aspect of the invention uses the encapsulation method for theintegration of devices (such as MEMS) through some sort of transferprocess. For example, in the case of amorphous silicon displays, theMEMS device might be fabricated on another substrate and latertransferred to the display substrate. Subsequent to this transfer thereare additional process steps to integrate the electrical and mechanicaldevices, followed by the final encapsulation process. Although LCDdisplays have been used as an example, in other aspects the presentinvention packaging technique can also be used OLED, electrophoretic,FED, and other types of displays.

In a different aspect, multiple device areas can be created using theabove-mentioned techniques to accomplish one of the following:

1) Packaging areas can be separated by functionality. For example, onepackaged device area can be a vacuum package, containing MEMS devicesrequiring a vacuum environment, and another is exposed to theenvironment (containing environment sensors), through holes drilled inone of the glass substrates.

2) Packaging areas can be separated by a defined distance, but linked byoperation. For example, a first device area might contain a MEMSmicrophone. A second, separate, device area might contain a second MEMSmicrophone. Because the exact spatial relationship between the devicesis controlled within the stringent limits of a photolithography process,the two devices can be coupled into a system solution. In the case ofmicrophone example, the acoustic input can be coupled and the knownmicrophone spatial relationship used to sense from where a particularsound is coming. The sound source data can be used to accomplish somedesired result.

MEMS on Glass

The use of glass substrates offers unique opportunities to producesurface novel micro machined devices and integrate them into systemlevel applications. Table 1 highlights some of the advantages of MEMS onglass over MEMS on silicon substrates.

TABLE 1 Comparison of Silicon vs. Glass substrates Silicon Attributesubstrate Glass substrate Cost moderate low Max substrate size (m²)1 >2.7 Optical properties Transparent to Transparent to all IRwavelengths Electrical insulation poor excellent Dielectric propertiespoor excellent Biological compatibility poor excellent Thermalinsulation poor excellent Max temperature 1400 C. 650 C.Crystallographic bulk yes no etch

MEMS on glass offer the following unique points:

1) The optical transparency of glass (other than its obvious advantagefor displays) permits the creation of novel MEMS devices. For example,it is possible to optically sense the motion of a device through thesubstrate without requiring through-holes or expensive packaging.

2) MEMS devices can be built on the same substrate as LC displays. Thisprovides opportunities to build other novel devices, such as integratedMEMS sensors on display.

3) Integrated RF on display One of the stumbling blocks when developingRF and electromagnetic MEMS devices is the effect of the siliconsubstrate. Typically, large quantities of substrate must be removed toimprove the quality of the MEMS device. By using a glass substrate, thisprocess is not necessary and the devices are simpler to manufacture andare more physically robust (since the substrate is intact).

4) Additionally, many MEMS processes need to take special steps toelectrically isolate individual moving elements from each other whenthey're all attached to the same conductive and parasitic substrate.Again, with glass, this isolation is inherently not necessary.

5) Micro-fluidic and biological applications often require materialsthat are bio-compatible, i.e. are biologically inert. Glass is one suchmaterial. It is simpler to start with a bio-compatible material (such asa glass substrate) than to use incompatible materials and coat them withappropriate surfaces.

6) Quite a few MEMS applications require thermal insulation betweenelements, such as bio-meters (IR sensors), field emission tips, andchemical detectors. With devices on a silicon substrate, much of thesubstrate must be removed to provide this thermal insulation. By using aglass substrate, each element is inherently isolated.

FIG. 11 is a flowchart illustrating a method for packaging a MEMSdevice. Although the method is depicted as a sequence of numbered stepsfor clarity, the numbering does not necessarily dictate the order of thesteps. It should be understood that some of these steps may be skipped,performed in parallel, or performed without the requirement ofmaintaining a strict order of sequence. Various steps in the method maybe better understood in the context of the explanations of FIGS. 1Athrough 10B, above. The method starts at Step 1100.

Step 1102 provides a first substrate having a first region withboundaries. Step 1104 forms an electrical circuit on a second region ofthe first substrate, electrically connected to the first substrate. Step1106 integrates a MEMS device on the first region, electricallyconnected to the first substrate. Some examples of MEMS devices includean acoustic speaker, a microphone, a radio frequency (RF) filter, an RFantenna, an accelerometer, a gyroscope, a chemical sensor, a temperaturesensor, a humidity sensor, a pressure sensor, a light sensor, aninfrared sensor, and an actuator. Step 1108 provides a second substrateoverlying the first substrate. Step 1110 forms a wall along the firstregion boundaries, between the first and second substrate.

In one aspect, forming the electrical circuit in Step 1104 includesforming an electrical device using thin-film processes. Step 1106integrates the MEMS device on the first region using thin-filmprocesses, simultaneous with the formation of the electrical device.Alternately, integrating the MEMS device on the first region in Step1106 includes substeps (not shown). Step 1106 a forms the MEMS device(i.e., in a process independent of the electrical circuit (Step 1104).Step 1106 b attaches the MEMS device to the first substrate firstregion. Step 1106 c forms electrical interconnections between the MEMSdevice and the first substrate using thin-film processes.

In one aspect, forming a wall along the first region boundaries in Step1110 includes enclosing the MEMS device between the first substrate, thesecond substrate, and the wall. For example, the MEMS device can behermetically enclosed.

In a different aspect, Step 1108 provides a second substrate having anopening overlying the first substrate first region. In this aspect, Step1106 integrates a MEMS environmental sensor. Step 1110 forms a wallalong the first region boundaries using the following substeps (notshown). Step 1110 a isolates the MEMS device from the electricalcircuit, and Step 1110 b exposes the MEMS device to a first environmentvia the second substrate opening. For example, Step 1106 may integrate amicro-fluidic MEMS, and Step 1110 b exposes the micro-fluidic MEMS to afluid environment.

In another example, Step 1104 forms an active circuit including a TFT,electrically connected to the MEMS. Then, forming a wall between thefirst and second substrate along the first region boundaries in Step1110 includes alternate substeps (not shown). Step 1110 c exposes theMEMS to a first environment. Step 1110 d exposes the TFT to a secondenvironment.

In another aspect, Step 1110 forms a wall along the first regionboundaries using the following substeps. Step 1110 e applies a sealantalong the first region boundaries, and Step 1110 f bonds the firstsubstrate to the second substrate. In one variation, Step 1110 g appliesuniformly shaped spacers to the first substrate and Step 1110 hmaintains a uniform distance between the first and second substrates inresponse to the spacers. Alternately, forming a wall in Step 1110includes other substeps. Step 1110 i forms a groove in the firstsubstrate along the first region boundaries, and Step 1110 j forms agroove in the second substrate, opposite the groove in the firstsubstrate. Then, Step 1110 k seats an O-ring in the first and secondsubstrate grooves. Note, the grooves may also be preformed in thesubstrates that are provided in Step 1102 and 1108.

In one specific example, Step 1102 provides a liquid crystal display(LCD) display substrate with a perimeter, and Step 1108 provides a colorfilter substrate with a perimeter. Then, Step 1112 seals the displaysubstrate to the color filter substrate along the perimeters to form acavity. Step 1114 fills the cavity with a liquid crystal material. Inone variation of this example, Step 1108 provides a color filtersubstrate having an opening through the substrate, overlying the firstsubstrate first region, and Step integrates a MEMS microphone.

In another aspect, Step 1102 provides a first substrate with a pluralityof regions with boundaries, and Step 1106 integrates a plurality of MEMSdevices on the first substrate, each in a corresponding region. Then,Step 1110 forms a wall around the boundaries of each region of the firstsubstrate.

In another aspect, forming a wall along the first region boundaries inStep 1110 includes: providing a boundary assembly having a shapematching the first region boundaries and a height; and, attaching theboundary assembly to the first substrate, overlying the first regionboundaries, separating the first substrate from the second substrate bythe boundary assembly height.

An integrated MEMS package and MEMS packaging method have been provided.Examples of particular MEMS devices and electrical circuits have beengiven to help illustrate the invention. However, the invention is notlimited to merely these examples. Other variations and embodiments ofthe invention will occur to those skilled in the art.

1. An integrated microelectromechanical system (MEMS) device package,the MEMS integrated package comprising: a first substrate having a firstregion with boundaries; an electrical circuit on a second region of thefirst substrate, electrically connected to the first substrate; a MEMSdevice environmental sensor on the first region, electrically connectedto the first substrate; a second substrate overlying the firstsubstrate, having an opening overlying the first substrate first region,exposing the MEMS device to a first environment via the second substrateopening; and, a wall along the first region boundaries, between thefirst and second substrates, isolating the MEMS device from theelectrical circuit.
 2. The MEMS integrated package of claim 1 whereinthe wall encloses the MEMS device between the first and secondsubstrates along the first region boundaries.
 3. The MEMS integratedpackage of claim 1 wherein the MEMS is a micro-fluidic MEMS; and,wherein the second substrate opening exposes the micro-fluidic MEMS to afluid environment.
 4. The MEMS integrated package of claim 1 wherein theelectrical circuit on the second region of the first substrate is anactive circuit including a TFT, electrically connected to the MEMS; and,wherein the wall separates the TFT, exposed to a first environment, fromthe MEMS, exposed to a second environment.
 5. The MEMS integratedpackage of claim 1 wherein the wall is a cured sealant.
 6. The MEMSintegrated package of claim 1 further comprising: a plurality ofuniform-shaped spacers applied to the first substrate; and, wherein thewall is a cured sealant, with a uniform height between the first andsecond substrates, response to the spacers.
 7. The MEMS integratedpackage of claim 1 wherein the first substrate includes a plurality ofregions with boundaries; the MEMS integrated package further comprising:a plurality of MEMS devices on the first substrate, each in acorresponding region; and, a plurality of walls, each wall formed aroundthe boundaries of a corresponding region of the first substrate.
 8. TheMEMS integrated package of claim 1 further comprising: a boundaryassembly shape matching the first region boundaries, and having aheight; and, wherein the wall comprises the boundary assembly attachedto the first substrate along the first region boundaries, separating thefirst substrate from the second substrate by the boundary assemblyheight.
 9. An integrated microelectromechanical system (MEMS) devicepackage, the MEMS integrated package comprising: a liquid crystaldisplay (LCD) substrate having a perimeter and a first region withboundaries; an electrical circuit on a second region of the firstsubstrate, electrically connected to the first substrate; a MEMS deviceon the first region, electrically connected to the first substrate; acolor filter substrate overlying the LCD substrate; and, a seal formedalong the perimeters of the display substrate and color filtersubstrate; and, a cavity between the display substrate and the colorfilter substrate, bounded by the seal.
 10. The MEMS integrated packageof claim 9 further comprising: liquid crystal material in the cavity.11. The MEMS integrated package of claim 9 wherein the color filtersubstrate has an opening through the substrate, overlying the firstsubstrate first region; wherein the MEMS device is a MEMS microphone.12. The MEMS integrated package of claim 9 wherein the seal encloses theMEMS device between the LCD and color filter substrates along the firstregion boundaries.
 13. The MEMS integrated package of claim 9 whereinthe seal hermetically seals the MEMS device between the LCD and colorfilter substrates along the first region boundaries.
 14. The MEMSintegrated package of claim 9 wherein the MEMS device is selected fromthe group including an acoustic speaker, a microphone, a radio frequency(RF) filter, an RF antenna, an accelerometer, a gyroscope, a chemicalsensor, a temperature sensor, a humidity sensor, a pressure sensor, alight sensor, an infrared sensor, and an actuator.
 15. An integratedmicroelectromechanical system (MEMS) device package, the MEMS integratedpackage comprising: a first substrate having a first region and a grooveformed along first region boundaries; an electrical circuit on a secondregion of the first substrate, electrically connected to the firstsubstrate; a MEMS device on the first region, electrically connected tothe first substrate; a second substrate overlying the first substrate,with a groove formed in a region opposite the groove in the firstsubstrate; and, a wall formed from an O-ring seated in the first andsecond substrate grooves.
 16. The MEMS integrated package of claim 15wherein the O-ring wall encloses the MEMS device between the first andsecond substrates along the first region boundaries.
 17. The MEMSintegrated package of claim 16 wherein the O-ring wall hermeticallyseals the MEMS device between the first and second substrates along thefirst region boundaries.
 18. The MEMS integrated package of claim 15wherein the MEMS device is selected from the group including an acousticspeaker, a microphone, a radio frequency (RF) filter, an RF antenna, anaccelerometer, a gyroscope, a chemical sensor, a temperature sensor, ahumidity sensor, a pressure sensor, a light sensor, an infrared sensor,and an actuator.
 19. The MEMS integrated package of claim 15 wherein thesecond substrate has an opening overlying the first substrate firstregion, exposing the MEMS device to a first environment via the secondsubstrate opening; and wherein the O-ring wall isolates the MEMS devicefrom the electrical circuit.